TheFreeWindowsBMI Calculator is a free utility that will help you learn your Body Mass index (if you are underweight, overweight or an ideal weight for your height) and avoid health risks related with fat. This is a useful measurement for most persons over 18 years old, but it may not be valid in special occasions, e.g. for athletes, whose weight comes from muscles and not from fat. You can also learn the range of acceptable weight according to your BMI.